In the Specification of the U.S. Pat. No. 4,521,911, to Vance, filed in 1984, the Patentee stated:
"Various proposals have been made for reinforcing bulk containers in the regions of high stress concentrations and for preventing or minimizing seam leakage, but many of such proposals involve the use of additional fabric or reinforcing material, reduction in bag capacity or increase in time and cost of container production."
Not only have such proposals been made in the past, but there have been attempts by many to meet the commercial requirements of users of such containers. As the intended contents of the containers have significant value, the spoilage or loss of which being intolerable, a requirement has been made by users including in-plant and field tests by users, safety tests performed by intrastate and interstate authorities and tests designed and carried out by independent labs who offer recognized certification. Failure to pass a test required for certification of a container designated for a specific load may be re-submitted for certification of the same container for a less load and a lesser load certification may be obtained in such case.
The U.S. Pat. No. to Williamson, 4,224,970, U.S. Pat. Nos. 4,457,456 and 4,479,243, to Derby and Williamson, assigned to Super Sack Manufacturing of Dallas, Tex., based on Application filed as early as 1977 and 1979, each discloses loop-supported flexible bulk material containers.
Illustrative of the fact that there were many workers in the field for a period of almost one hundred years is the Patent to Lobdell, U.S. Pat. No. 546,168, which goes back to Sep. of 1895.
Early workers in the field, Rolaf Lehmann and Sven Burnmeister of Germany, U.S. Pat. No. 4,658,432, having a priority date of 1985, emphasized the need for strength particularly the need for passing a drop test wherein the height of the drop is measured as being 120 cm and the flexible woven polypropylene container carries a load of 1,250 kg which load is not to be damaged after the loaded container is dropped.
The Patent to Beaven and Barcoe, U.S. Pat. No. 4,301,848, having a priority of 1978, discloses a flexible container for bulk particulate materials having four supporting loops. The fabric of the side walls is oriented with the weft vertical and the warp horizontal when the bag is in the normal upright position.
The Patent to Sandeman and Bell of Scotland, U.S. Pat. No. 4,207,937, having a priority date of 1977, discloses a flexible bulk container for particulate materials made of woven polypropylene, utilizing special warp threads adjacent to selvages near seams for improvement in strength.
Prolific workers in the field were Yorkshiremen Frank and Peter Nattrass. See U.S. Pat. No. 3,961,655 having a priority date of 1973; U.S. Pat. No. 4,010,784 having a priority of 1973; U.S. Pat. No. 4,010,784 having a priority of 1973; U.S. Pat. No. 3,961,655, having a priority of 1973; U.S. Pat. No. 4,307,764, having a filing date of 1980; U.S. Pat. No. 4,364,424, having a filing date of 1981; U.S. Pat. No. 4,493,109, having a priority date of 1982; U.S. Pat. No. 4,597,102, having a priority date of 1984; U.S. Pat. No. 4,610,028, having a priority date of 1984; U.S. Pat. No. 4,646,375, having a filing date of 1985.
All The Nattrass Patents have to do with loop-supported flexible bulk material containers of woven polypropylene. Some of the structures are made of tubular fabric and some are mode with planar sides having vertical seams to which a supporting loop may be secured. It is to be expected that, in view of the early Nattrass priority dates, the British constructions, including the four loop-supported bags of these Yorkshiremen, have been publicly known for more than seventeen years.
The Patent to Walter Polett and Muriel Polett, U.S. Pat. No. 4,499,599, filed in 1983, has to do with a polypropylene flexible bulk container with supporting loops extending from one side of the container to the other side.
The Patent to Kraus, U.S. Pat. No. 4,081,011, having a Priority Date of 1976, discloses a flexible container with suspension elements extending from one side of the container to the opposite side.
The Patent to Sekiguchi, U.S. Pat. No. 5,356,583, having a Priority Date of 1979, van de Pol, U.S. Pat. No. 4,664,957, having a Priority Date of 1985, and Marino, U.S. Pat. No. 4,524,457, filed 1984; Platt, U.S. Pat. No. 4,480,766, filed 1982; and Marino, U.S. Pat. No. 4,703,517, filed in 1986, show miscellaneous further work in the field of loop-supported flexible bulk containers.
During the testing of the bags produced by the joint inventors of the instant Application, there was occasion to observe the testing of bags produced by competitors which bags initially failed and could only pass by reducing the load for which the bags were certified or by increasing the weight of the fabric with the attendant increase in expense.
The bags made by the joint inventors passed the necessary load, drop, and other pertinent tests in a manner superior to what was observed of the testing of bags produced by competitors.
Although bags of the character of the flexible intermediate bulk container category were produced and utilized for many years in foreign countries and in particular in England and the European continent, the FIBC industry in the United States is relatively new and industry standards in the U.S. have not been greatly advanced.